1. Field of the Invention
This utility model relates to a vial to contain exactly metered quantities of chemical reagents, in particular high purity chemical reagents of exactly defined concentration, for use in carrying out chemical reactions and/or titrations after predetermined dilution.
2. Discussion of the Related Art
Vials of this type are well known and widely used in chemical and analysis laboratories.
Known vials consist of an elongate hollow body closed at its two ends by breakable membranes. Or, that end of the vial which is to remain at the higher level during the use of the vial (hereinafter known as the upper end), there is usually mounted a furreel provided with a cutting edge to break the membrane adjacent to it, the funnel being used to feed wash water to the vial after the reagent originally contained in it has been discharged (see patents EP-A-0 213 559, EP-A-0 332 914, US-A-4 964 521 and US-A-5 178 838).
In contrast, the closure systems vary greatly for that end of the vial which is to face downwards when the reagent is discharged from it, this being known hereinafter as the lower end of the vial.
EP-A-0 213 559 illustrates a vial the lower end of which is sealedly closed by a membrane identical to that provided at its upper end and also breakable by a cutting edge projecting from a funnel member mounted on the lower end of the vial. With this system the main drawback is that it is very easy to accidentally and dangerously break the membrane which can result in a very dangerous leakage of the reagent from the vial.
EP-A-0332914 and US-A-4964521 illustrate a vial the lower end of which is sealedly closed by a membrane welded to a stronger membrane or part provided at the discharge end of a funnel member mounted on the end of the hollow body to which it is connected by a spiral rib. On rotating the funnel member relative to the hollow body, the closure membrane is torn from the lower end of the vial to allow discharge of the reagent.
This type of vial has two main drawbacks, namely that the membrane of the hollow body has to be properly welded to that of the funnel member, and that a non-negligible quantity of the reagent remains trapped between the lower end of the hollow body and the funnel member mounted on it.
In addition, none of the aforesaid vials can be reclosed (at their lower end) after being opened.
US-A-5178838 comprises, at the lower end of the vial described in it, a device of a tap type comprising two mutually cooperating conical surfaces, which can be pressed one against the other close the vial or withdrawn one from the other to enable the reagent contained in it to be discharged. This type of tap device has the merit of enabling the flow of reagent from the vial to be interrupted at any moment, but has the drawback of being relatively costly, of suffering from undesirable and dangerous leakage (especially during transportation of the vial), and of retaining portions of the reagent which drip to the outside after the tap device has been closed.